It is desired that a motor control device controlling driving of an electric motor of an electric power steering device or an electric motor of an electric braking device mounted in a vehicle, a traveling electric motor of an electric vehicle or a hybrid vehicle, or the like can continue to drive the electric motor even when something abnormal occurs in a motor control system.
In order to meet the desire, an electric power steering device has been proposed that has a configuration in which along with a duplex inverter for supplying a motor driving current to a multi-phase electric motor, a power source relay is provided between a power source and each inverter, and a motor relay is provided between each inverter and a motor winding of each phase of the multi-phase electric motor (for example, see PTL 1).
When something abnormal occurs in switching means of one or more inverter units, the electric power steering device causes the power source relay and the motor relay to perform a blocking operation to block energization between the abnormal inverter and the power source and energization between the inverter and the multi-phase electric motor.
In addition, during normal control for assisting steering of a steering wheel, the electric power steering device causes the power source relay to block energization between the device and the power source, and monitors a voltage of a wire connecting the power source relay to the motor to check a short-circuit failure of the power source relay.
Additionally, the electric power steering device causes the motor relay to block energization between the device and the motor during the normal control for assisting the steering of the steering wheel, and monitors a voltage of a wire connecting the motor relay to the motor to check a short-circuit failure of the motor relay.